The University of California, San Diego Pediatric AIDS Clinical Trials Unit (UCSD Pediatric ACTU) proposes to continue its participation in the AIDS Clinical Trials Group (ACTG) of the National Institute of Allergy and Infectious Diseases. We have hired an outstanding group of health- professionals, established clinical programs and developed outreach activities that are necessary for the implementation and successful completion of clinical studies for HIV-infected children. Members of the UCSD Pediatric ACTU have made important contributions to the planning, development, implementation and analysis of clinical studies encompassing a broad range of ACTG pediatric protocols. Additionally, members of our Unit have participated in 19 different ACTG committees and working groups, and have been members of 13 different protocol teams. We propose to continue our high-level of participation in studies: to evaluate antiretrovirals, to prevent and treat opportunistic infections and serious bacterial infections, and to prevent maternal-infant transmission. Additionally, we will initiate studies to evaluate candidate HIV vaccines when they become available. All children and pregnant women infected with HIV followed by our Mother/Child clinic are potentially eligible for participation in ACTG protocols. Thus, participants recruited to clinical studies are representative of populations most affected by the AIDS epidemic in San Diego County including minority women and children, substance users, and persons with hemophilia. The continued participation of the UCSD Pediatric ACTU in the ACTG will enable our Unit to continue to make important contributions to the overall effort to develop improved treatments for women and children infected with HIV.